A Logarithmic Conformal Field Theory Solution For Two Dimensional Magnetohydrodynamics In Presence of The Alf'ven Effect

When Alf`ven effect is peresent in magnetohydrodynamics one is naturally lead to consider conformal field theories, which have logarithmic terms in their correlation functions. We discuss the implications of such logarithmic terms and find a unique conformal field theory with centeral charge $c=-\frac{209}{7}$, within the border of the minimal series, which satisfies all the constraints. The energy espectrum is found to be \newline $E(k)\sim k^{-\frac{13}{7}} \log{k}$.Comment: Latex, 9 page

The prevalence of stuttering, voice disorder and speech sound disorders in preschoolers in Shahrkord, Iran

Abstract: The inability to communicate easily and clearly can have far-reaching debilitating effects, not only in childhood, but throughout a lifetime. The aim of this study was to determine the prevalence of stuttering, voice disorder, and speech sound disorders in Persian preschoolers in Shahrekord, Iran. Information about 1,387 children ages 5 to 6 was obtained via face-to-face screening and assessment. The total prevalence of speech disorders was 17.1%. The prevalence of stuttering was 1.5%, while 13.4% had a speech sound disorder, and 2.2% had voice disorder. The prevalence of stuttering was higher in males (2.2%) than females (0.7%); of speech sound disorders was higher in males (17.4%) than females (9.1%); and of voice disorder was higher in males (2.6%) than females (1.6%). The prevalence of stuttering and speech sound disorder was significantly different according to gender and positive family history. The prevalence figures revealed that a considerable number of preschoolers with speech disorders were missed in parents’ and teachers’ reports. Those children required more intensive communication support than they were receiving. Therefore, classroom teachers should work with speech and language pathologists to identify and assess preschoolers with communication disorders, and to develop intervention strategies

A Compact Electromagnetic Vibration Harvesting System with High Performance Interface Electronics

A compact vibration-based electromagnetic (EM) energy harvesting system utilizing high performance interface electronics, has been presented. The energy harvester module consists of an AA-battery sized cylinder tube with an external coil winding, a fixed magnet at the bottom of the tube, and a free magnet inside. The transducer is able to operate at low external vibration frequencies between 9.5 and 12 Hz. The generated AC voltage is converted to DC using a custom rectifier circuit that utilizes a gate cross coupled (GCC) input stage. This decreases the effective threshold voltage of the utilized diodes, while increasing the DC output power delivered to the load. The autonomous system, composed of an EM energy harvester module and a 0.35 mu m CMOS IC, delivers 11.6 mu W power to a 41 mu A load at an external vibration frequency of 12 Hz. The volume of the total system is 4.5 cm(3), and the overall system power density is 2.6 mu W/cm(3)

Electrical power production from low-grade waste heat using a thermally regenerative ethylenediamine battery

Thermally regenerative ammonia-based batteries (TRABs) have been developed to harvest low-grade waste heat as electricity. To improve the power production and anodic coulombic efficiency, the use of ethylenediamine as an alternative ligand to ammonia was explored here. The power density of the ethylenediamine-based battery (TRENB) was 85 \ub1 3 W m2-electrode area with 2 M ethylenediamine, and 119 \ub14Wm2 with 3 M ethylenediamine. This power density was 68% higher than that of TRAB. The energy density was 478 Wh m3-anolyte, which was ~50% higher than that produced by TRAB. The anodic coulombic efficiency of the TRENB was 77 \ub1 2%, which was more than twice that obtained using ammonia in a TRAB (35%). The higher anodic efficiency reduced the difference between the anode dissolution and cathode deposition rates, resulting in a process more suitable for closed loop operation. The thermal-electric efficiency based on ethylenediamine separation using waste heat was estimated to be 0.52%, which was lower than that of TRAB (0.86%), mainly due to the more complex separation process. However, this energy recovery could likely be improved through optimization of the ethylenediamine separation process

Equilibrium current vortices in rare-earth-doped simple metals

Dilute alloys of rare earths have played a vital role in understanding magnetic phenomena. Here, we model the ground state of dilute 4f rare-earth impurities in light metals. When the 4f subshells are open (but not half-filled), the spin-orbit coupling imprints a rotational charge current of conduction electrons around rare-earth atoms. The sign and amplitude of the current oscillate similar to the RKKY spin polarization. We compute the observable effect, namely the Oersted field generated by the current vortices and the Knight shift.Comment: Format: Long articl

Controlling surface statistical properties using bias voltage: Atomic force microscopy and stochastic analysis

The effect of bias voltages on the statistical properties of rough surfaces has been studied using atomic force microscopy technique and its stochastic analysis. We have characterized the complexity of the height fluctuation of a rough surface by the stochastic parameters such as roughness exponent, level crossing, and drift and diffusion coefficients as a function of the applied bias voltage. It is shown that these statistical as well as microstructural parameters can also explain the macroscopic property of a surface. Furthermore, the tip convolution effect on the stochastic parameters has been examined.Comment: 8 pages, 11 figures

Long range correlation in cosmic microwave background radiation

We investigate the statistical anisotropy and Gaussianity of temperature fluctuations of Cosmic Microwave Background radiation (CMB) data from {\it Wilkinson Microwave Anisotropy Probe} survey, using the multifractal detrended fluctuation analysis, rescaled range and scaled windowed variance methods. The multifractal detrended fluctuation analysis shows that CMB fluctuations has a long range correlation function with a multifractal behavior. By comparing the shuffled and surrogate series of CMB data, we conclude that the multifractality nature of temperature fluctuation of CMB is mainly due to the long-range correlations and the map is consistent with a Gaussian distribution.Comment: 10 pages, 7 figures, V2: Added comments, references and major correction